Automatic alarm transmitter



May 24, 19 J. 1.. CASSELL AUTOMATIC ALARM TRANSMITTER 3 Sheets-Sheet 1Filed Sept. 14, 1954 INVENTOR. JOSEPH L. CASSELL ATTORNEY May 24, 1960J. CASSELL AUTOMATIC ALARM TRANSMITTER 3 Sheets-Sheet 2 Filed Sept. 14,1954 l-OS FIG.3

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mmvron JOSEPH L. CASSELL ATTORNEY May 24, 1960 .1. 1.. CASSELL AUTOMATICALARM TRANSMITTER 5 Sheets-Sheet 3 Filed Sept. 14. 1954 FIG. e

FIG.7

L R RS 05 TA MC L m a Q J ATTORNEY 2,938,197 AUTOMATIC ALARM TRANSMITTERJoseph L. Cassell, New York, N.Y., assignor to Automafic Fire AlarmCompany, New York, N.Y., a corporation of New York Filed Sept. 14, 1954, Ser. No. 456,033

12 Claims. 01. 340-288) The invention herein disclosed relates tosignaling apparatusparticularly for transmitting coded signals to acentral oifice.

While of special importance for fire alarm systems, the invention is notlimited to that field but may be applied to burglar alarm systems orother types of signaling equipment.

mitter itself may be built in a single standard form, and

then just before being connected for service or possibly just beforeshipment from the factory, may be quickly and conveniently arranged toprovide the proper retard time either for the waterflow or for the aerotype of fire alarm system.

Actuallythis final provision of the proper retard interval may bedetermined by the simple expedient of selecting and applying a nameplateeither of non-conductive or conductive material and which in the firstinstance will leave a normally charged capacitor free to discharge forthe full retard time, say thirty seconds for a Waterfiow system, or inthe second instance will shunt a resistance across the capacitor toreduce the retard time, say to twelve seconds for an aero or other suchsystem.

Other special features and objects of the invention relate to theso-called fire clock and trouble clock and to the maintaining of thesein cooperative but independently active relation, the fire clock beingcapable at all times of sending in a fire signal and the trouble clockcapable at all times of signalling a break or ground, or both, andfurther, in the event of a break or a ground, automatically establishinga special trouble circuit condition after transmission of the troublesignal which special circuit condition permits the fire clock to operatein response to an alarm signal notwithstanding the presence of the opencircuit or ground condition on the protective circuits.

7 Other features of the. invention relate to the tamper switch which isheld closed by the door of the enclosure in which the transmitter is"mounted and which through the cooperating of certain cam mechanism ofthe trouble clock, enables the door to be completely closed before thetrouble clock, after having been fully wound with the door open, can rundown beyond its starting condition.

.Another important feature of the invention is the provision of arectifier protecting the capacitor against damage from reversal ofpolarity and insuring that the transmitter, after installation andinspection, will always be ,left with the current supply connected inthe correct polarity for normal operation of the system.

Other special features of the'iuvention relate to con- Unitecl StatesPatent 2,938,197 Patented May 24, 1960 2 trol relays and circuits,'oneinstance in particular in which a current relay transfers the centraloflice wires to a current failure signal wheel on the fire clock, thusto prevent a clash of signals which might otherwise result fromsimultaneous operation of the trouble clock with the fire clock, on lossof supply current.

Other desirable objects and novel features of the invention are setforth and will appear in the course of the following specification.

' The drawings accompanying and forming part of the specificationillustrate a present practical embodiment of the invention and circuitconnections applicable thereto. Construction, combination and relationof parts, however, may be modified and changed as regards the immediateillustration, all within the true intent and scope of the invention ashereinafter defined and claimed.

Fig. 1 in the drawings is a front or face view of the bare transmitter,that is, the insulating panel forming the base of the instrument and thevarious mechanical and electrical parts mounted on the panel, allconstitut- Lug a single unit adapted to be mounted in an alarm Fig. 2 isa circuit diagram of parts shown in Fig. 1;

Fig. 3 is a simplified diagram illustrating action of the transmitter ina typical alarm system;

Figs. 4 and S are fragmentary sectional detail views taken on the line4-4 of Fig. 1, showing the selective use of metal and insulatingnameplates to control the retard time.- I

Figs. 6 and 7 are fragmentary perspective views illustrating controlfeatures of the fire clock and trouble clock, respectively.

In Fig. 1, there is shown a total of sixteen screw type terminalsnumbered 1 to 16, mounted on a panel 18 of suitable insulating material.Near the corners of the panel 18 are mounting screws 19 for securing thepanel in a suitable protective enclosure such as a metal cabinet (notshown). This cabinet will ordinarily be provided with a hinged door foraccess to the transmitter, provision being made for locking the door inits closed position. A tamper switch 20 is actuated by the door. Thetamper switch 2%) is a three position switch having two closed positionsand a single open position. With the cabinet door closed, the tamperswitch 20 is closed as shown'in Fig. 2. When the cabinet door is opened,the tamper switch 20;is automatically spring pressed to its openposition. With the door open, the tamper switch may be manually operatedto its closed position for 'purposes of testing and maintenance.

Mounted on the face of the panel 18 are two spring driven clockworkmechanisms one being a fire clock designated generally as 1-00 and theother a trouble clock designated generally as 2-00. These mechanisms areprovided with key operable winding stems 1-01, 201, escapements 1-02,and 2-02 and release magnets 1-03 and 24B, respectively. The releasemagnets 103 and 2-03 are provided with colresponding operating windings1-04 and 2-04 (Fig. 2).

The fire clock 1-00 is shown, Figure 6, as having a front code wheel1-05 and a rear code wheel 1-06 mounted on a common code 'wheel shaft1-07. The front code wheel 1-05 controls a set of contact springs 1-08and the rear code wheel 1-06 controls a set of contact springs 1-09. Thefire clock 1-00 also comprises a reduced speed cam shaft 1-10 which isdriven along with the code wheel shaft 1-07 by the clockwork mechanism.The cam shaft 1-10 will ordinarily revolve at one-fifth of the speed ofthe code wheel shaft 1-07. The cam shaft 1-10 carries a cam 1-11 formedof insulating material. Shortly after the beginning of operation of thefire clock mechanism, the cam 1- 11 will close two pairs of contactsprings 1-12 and ;1-.13

and a cam 2-06 mounted on a common code wheel shaft 2-07. The code wheel'2-05 controls a set of contact springs 2-08. The cam 2-06 controls aset ofcontact springs 2-09. There is also a radially proiectingarrn 2-10mounted on thespring winding shaft 2-01. The

arm 2-10 is arranged to. actuate contact springs after the trouble clock2-00 has unwound to the extent of completing its signal transmissioncycle. There are two pairs of normally .open run-down contacts 12-11 and2-12 which are closed by the arm 2-10 and two pairs of normally closedrun-down contacts 2-13 and 2-14 which are opened by action of the arm2-10 when the trouble clock 2-00 is unwound.

As shown in Fig. 1, there is an electrolytic capacitor 36, mounted onthe front of the panel 18 between the fire clock 1-00 and the troubleclock 2-00.

Mounted on the upper portion of the panel 18 are three relays. An alarmrelay 3-00 is located above the fire clock 1-00. A trouble relay 4-00 islocated above the trouble clock 2-00. A power failure or current supplysupervisory relay 5-00 is located above the capacitor 36.

The alarm relay 3-00 comprises an operating winding 3-01 and a singlepair of contacts 3-02. The operating winding 3-01 is normally energizedholding the contacts 3-02 normally closed. Upon deenergization of theoperating winding 3-01, the alarm relay contacts 3-02 will open.

The trouble relay 4-00 comprisw an operating winding 4-01 and a singleset of transfer contacts consisting of a movable or transfer contact4-02, a contact 4-03 which is engaged by contact 4-02 when the winding4-01 is energized and a contact 4-04 which is engaged by the movablecontact 4-02 when the winding 4-01 is deenergized.

The power failure or current supervisory relay 5-00 comprises anoperating winding 5-01, two sets of transfer contacts and a further setof contacts. One set of transfer contacts comprises a movable contact5-02 which engages a contact 5-03 when winding 5-01 is energized andengages another contact 5-04 when the winding 5-01 is deenergized. Theother set of transfer contacts comprises a movable contact 5-05 whichengages a contact 5-06 when the winding 5-01 is energized and engagesanother contact 5-07 when winding 5-01 is deenergized. The further setof contacts 5-08 is closed when the winding 5-01 is energized.

In the face view of the transmitter givenin Fig. 1

all of the apparatus is shown in its completely decnergized condition.All relay windings are deenergized. Both of the clock mechanisms 1-00and 2-00 are unwound. The arm 2-10 is shown actuating the run downcontact springs so as to close the normally open run-down contacts 2-11and 2-12 and to open the normally closed run-down contacts 2-13 and2-14.

In Fig. 2, the apparatus is shown in its normal operative condition,ready to transmit either a fire signal or a trouble signal. 7

In in this view, terminals 7 and 8 are indicated as being connected to asuitable source of 12 volts direct current illustratively shown as anungrounded battery 21, Fig. 3. The operating winding 5-01 of the powerfailure or current supervisory relay 5-00 is connected directly to thesupply terminals 7 .and 8 so that it is continuously energized so longas there is no failure of the 12 volt supply 21. The operating winding1-04 for the release magnet 1-03 of the fire clock 1-00 is connecteddirectly in series with the contacts 5-08 of the power failure relay5-00 so that the fire clock will be tripped immediately in the event ofcurrent failure. The movable transfer contacts 5-02 and 5-05 of thepower failure relay 5-00 are connected directly by conductors 22 and 23to panel terminals 11 and 12 which, in turn, are connected to aconventional McCullogh central oflice circuit 24 which is normallyclosed. Under normal conditions, conductors 22 and 23 are connectedthrough relay con tacts 5-02, 5-03 and 5-05, 5-06 to the seriallyconnected code-wheel actuated contact springs 1-08 and 2-08 of the fireclock and trouble clock 1-00 and 2-00, respec- "tively. The sets ofcontact springs 1-08 and 2-08 are connected in series with each otherand are actuated by the code wheels 1-05 and 2-05, respectively, for theseparate transmission of fire alarm and trouble signals with power frombattery 21 available at panel terminals 7 and 8. Upon power failure,however, the central office circuit 24 is transferred via relay contacts5-02, 5-04 and 5-05, 5-07 to the contact springs 1-09 of the fire clockwhich are actuated by the special power failure signal code wheel 1-06of the fire clock 1-00. As previously noted, the circuit of theoperating winding 1-04 of the release magnet 1-03 of the fire clock 1-00is opened simultaneously with the transfer of the central oflice circuitto the special power failure signal contacts 1-09 so that the powerfailure signal is transmitted immediately by the fire clock mechanism1-00. During power failure conditions with the relay 5-00 released, thefire signal codewheel contacts 1-08 and trouble signal code-wheelcontacts 2-08 are both completely disconnected from the central oflicecircuit 24. It will be noted that this circuit is normally ungroundedand that the grounding only occurs when the first tooth of the codewheel touches the actuating spring.

Under normal conditions, the negative side of the 12 volt supply 21 atpanel terminal 7 is connected to ground through panel terminals 9 and 10by the normally closed run-down contacts 2-13 of the trouble clock 2-00.Thus, under normal conditions, the negative side of the 12 volt powersupply is grounded. The negative panel terminal 7 is connected by aconductor 25 to one side of the operating winding 4-01 of the troublerelay 4-00. The operating winding 4-01 is the last circuit elementconnected to the negative supply conductor 25 so that any break inconductor 25 which would render other circuit elements inoperative willalso deenergize the trouble relay 4-00 and cause a trouble signal to betransmitted.

The positive panel terminal 8 is continuously connected to the otherside of the winding 4-01 of trouble relay 4-00 by a supervisory circuitwhich is traceable via a conductor 27 and through a resistor 28 to thepanel terminal 5. From terminal 5, the circuit extends over a house loopconductor 46 and back to panel terminal 4. From terminal 4, the circuitextends locally at the transmitter panellB through the operating winding3-01 of the alarm relay 3-00 and a resistor 29 to panel terminal 1. Frompanel terminal 1, the supervisory circuit extends through the tamperswitch 20 to panel terminal 2 and through a jumper from panel terminal 2to terminal 3'. From panel terminal 3, the closed supervisory circuitcontinues over another house loop conductor 45 to panel terminal 6 andfrom terminal 6 via a conductor 30 to the positive side of winding 4-01of the trouble relay 4-00. Obviously, any break in this closedsupervisory circuit will deeuergize the winding 4-01 of trouble relay4-00. Similarly, a ground on any portion of this supervisory circuitfrom panel terminal 8 to the positive side of trouble relay winding 4-01will deenergize winding 4-01 and actuate the trouble relay 4430 becausethe negatit e side of winding 4-01 is grounded through trouble clockrun-down contacts 22-13 as described above.

The two house loop conductors 45 and 46 thus form a two-wire circuitthrough which the supervisory circuit extends from the panel 18 to thecontacts of an alarm signal device 47 and back to the winding 3-01 ofthe alarm relay. The alarm signal device comprises normally opencontacts connected between the two sides of the and the transmitter willbe inoperative. will observe this situation and reverse the connectionsat I double ended' loop or two-wire circuit portion of the supervisorycircuit constituted by the house loop conductors 45 and 46. The alarmswitch 47, which may illustratively be considered to be operated bywater flow actuated means in an automatic sprinkler system,whenoperated, will connect house loop conductors 45 and 46 together sothat the winding 3-01 of the alarm relay 3-00 is shunted and the alarmrelay 3-00 then releases opening its contacts 3-02.

Opening of alarm relay contacts 3-02 interrupts an energizing circuitfor the winding 1-04 of fire clock release magnet 1-03. This energizingcircuit extends from the positive supply conductor 27, alarm relaycontacts 3-02, a conductor 33, a rectifier 44 and power failure relaycontacts 5-08 to the positive side of release magnet winding 1-04. Thenegative side of the release magnet winding 1-04 is permanentlyconnected to negative panel terminal 7 by the negative supply conductor25. However, interruption of this energizing circuit does notimmediately release the magnet 1-03 because its winding 1-04 continuesto receive current from the charged capacitor 36 through a resistor 31.The discharge path of capacitor 36 consists solely of the fire clockrelease magnet winding 1-04 and the total resistance of this winding andresistor 31'is sufficiently high so that the clock 1-00 will nottransmit the fire signal until a delay of about 30 seconds has elapsedfrom the instant of opening of the alarm relay contacts 3-02. It will beobserved the capacitor 36 is normally continuously energized through theclosed contacts 3-02 of the alarm relay 3-00 through conductor 33 andthe series resistor 31 so that it is always ready to continue theenergization of the fire .clock release magnet winding 1-04 for a thirtysecond interval following the opening of alarm relay contacts 3-02. Thisthirty second interval of prolonged energization has been found to besatisfactory in practice to prevent the transmission of false fire alarmsignals as a result of water hammer effects in -the automatic sprinklersystem which causes closure of the contacts of the alarm signal device47. The resistor 31 in series with capacitor 36 is a current limitingresistor which prevents excessive current flow through relay contacts3-02 or 4-02, for example, during charging and discharging of thecapacitor and particularly in the event of an accidental short circuitcaused by dielectric failure within the capacitor.

-Additionally, if the electrolytic capacitor 36 should break down,resistor .31 prevents short-circuiting of the fire clock-release magnetwinding 1-04 and thus avoids the transmission of a false fire signal.

The rectifier 44 serves as a protective device to prevent damage to thecapacitor 36 by any inadvertent connection of the power supply to panelterminals 7 and 8 with reversed polarity. In such event, the rectifierprevents sufficient reverse current flow to damage the electolyticcapacitor 36 and the current flow through the winding '1-04 of'the fireclock release magnet 1-03 is insufiicient to'en'ergize the releasemagnet. As a result, the fire clock magnet 1-03 will remain releasedwith reversed polarity The installer panel terminals 7 and 8 in order toobtain the correct polarity and proper operation of the transmitter.

Fire signal transmission In the event of fire, water flow in thesprinkler system will cause the contacts of the. alarm signal device 47to close and to remain closed continuously during period of water flow.Closure of the contacts of the alarm signal device 47 connects thehouseloop conductors 45 and 46 together and thereby shunts out the operatingwinding 3 -01 of the alarm relay 3-00. Current fiow through theoperating winding 4-01 of the trouble relay 4-00 is increased somewhatby a reduction in the resistance of the supervisory circuit describedabove. This resistance reduction is effected by the exclusion-from thesupervisory .deenergized and the fire clock mechanism is released totransmit four rounds of the alarm signal from contacts 1-08 actuated bythe from code wheel 1-05 of the fire clock 1-00.

The trouble clock release magnet 2-03 remains energized because thetrouble relay 4-00 remains operated, as previously described, and itscontacts 4-02, 4-03 which control the release magnet winding 2-04 remainclosed. The code wheel actuated contacts 2-08 of the trouble clock 2-00which are in series with the active fire clock code wheel contacts 1-09therefore remain inactive and closed so that there is no interference bythe trouble clock 2-00 with the transmission of the fire signal by thefire clock l-00. After the transmission of four rounds ofthe fire signalhas been completed by the fire-clock 1-00, detent mechanism (not shown)cooperating with the notch 1-14 in the wheel 1-15 prevents furtheroperation of the fire clock 1-00. During this transmission of the fourrounds of the fire signal by the code wheel 1-05 of the fire clock 1-00,the auxiliary contacts 1-12 and 1-13 are held closed. These contacts arenormally open and are closed by the cam 1-11 only during the actualtransmission of the four rounds of fire signal. Before and after thetransmission of the four rounds of the fire signal, the contacts 1-12and 1-13 are open. The Local contacts 1-12 are usually connected tooperate a locking relay (not shown) controlling a warning bell locatedin the building engineers ofiice or at some other normally attendedplace in the protected premises. The Shunt" contacts 1-13 are used toshunt out other transmitters on the same central otfice circuit.

After the fire condition has been cleared and the system is restored tonormal, re-energization of the fire clock release magnet 1-03 causes thefire clock to transmit a single round of the fire signal, this beingeffected by the detent mechanismwhich cooperates with the notched wheel1-15 on the cam shaft 1-10. Because of the 5:1 ratio between the speedsof the code wheel shaft 1-07 and the cam shaft 1-10, the transmission ofthe single round of the fire signal following the four rounds brings thecam shaft 1-10 and the cam 1-11 to the initial or starting position. Thesingle round also informs the operator at the central ofiice that thetransmitter has been restored to normal and that it is back in service,ready to transmit another fire signal.

Open circuit trouble condition Assume, for example, that there has beena break in one of the house loop conductors 45 or 46. This break opensthe closed supervisory circuit described above in connection with thetrouble relay 4-00 and deenergizes the operating winding 4-01 of thetrouble relay. At the same time, the operating winding 3-01 of the alarmrelay is also decnergized because this winding is likewise included inthe supervisory circuit. The broken circuit condition thus releases boththe alarm relay 3-00 and the trouble relay 4-00 simultaneously.

Release of the alarm relay 3-00 causes it to open its contacts 3-02thereby interrupting the supply of current to the fire clock releasemagnet winding 1-04. However, release of the trouble relay causesclosure of trouble relay contacts 4-02 and 4-04. Closure of troublerelay contacts 4-02 and 4-04 energizes the fire clock release magnetwinding 1-04 through an alternate circuit extending from panel terminal8 through trouble relay contacts 4-02, 4-04, a conductor 32, thenormally closed trouble clock run-down contacts 2-14 and rectifier 44.The capacitor 36 is thus maintained fully charged and the fire cloc'krelease magnet 1-03 remains energized notwithstanding release of thealarm relay 3-00.

Release of the trouble relay 3-00 causes it to open its contacts 4-02,4-03 which are normally closed and thus deenergize the trouble clockrelease magnet winding 2-04. The trouble clock 2-00 thereupon operatesto transmit a single round of the trouble signal by means of its codewheel actuated contacts 2-08. As previously noted, the fire clockrelease magnet winding is held energized by release of the trouble relay4-00 so that code wheel actuated contacts 1-08 of the fire clock remaininactive. Since the code wheel actuated contacts 1-08 of the fire clockand 2-08 of the trouble clock are connected inseries with each other, itis essential that one set of contacts shall remain inactive and closedwhile the other set of contacts is in operation.

After the single round of the trouble signal has been transmitted, thearm 2-10 of the trouble clock opens the normally closed trouble clockrun-down contacts 2-13 and '2-14 and closes the normally open contacts2-11 and 2-12. This actuation of the run-down contacts transfers thecircuit from the normal condition shown in Fig. 2 to the troublecondition shown in Fig. 3. In Fig. 3, the circuit through the tamperswitch 20 and panel terminal 2 has been omitted for simplicity ofillustration, panel terminal 1 being shown connected directly to panelterminal 3.

With the circuit rearranged by operation of the rundown contacts 2-11 to2-14, the normal ground connection to the negative side of the currentsupply at terminal 7 is broken by contacts 2-13. The system is thusconverted to a system with an ungrounded power supply.

Both ends of the house loop conductor 45 are connected together byrun-down contacts 2-11. Both ends of the other house loop conductor 46are connected together by run-down contacts 2-12. With single break ineither or both of the house loop conductors 45 and 46, the contacts ofthe alarm signal device 47 will nevertheless be connected to panelterminals 3 and 4, either directly or through panel terminals 5 and 6and the closed run-down contacts 2-12, 2-11 of the trouble clock 2-00.The other set of run-down contacts 2-14 disconnects the circuit of thefire clock release magnet winding 1-04 from trouble relay contact 4-04so that the winding 1-04 is entirely independent of the condition oftrouble relay 4-00. The fire clock release magnet winding 1-04 will thusbe continuously energized so long as the alarm relay 3-00 is operated.The trouble relay 4-00 is no longer needed because the trouble clock2-00 has already transmitted the trouble signal to the central ofice andhas actuated its run-down contacts to set up the trouble circuitcondition shown in Fig. 3.

. Assuming the broken connection to be in house conductor 46 asindicated at 41 in the trouble circuit condition, there is established aclosed circuit from the positive panel terminal 8 through run-downcontacts 2-11, winding 3-01 of alarm relay 3-00, resistor 29, run-downcontacts 2-12 and the winding 4-01 of trouble relay 4-00 to the negativepanel terminal 7. Although the alarm device 47 is disconnected frompanel terminal 3 by the break in house loop conductor 46 at 49, thealarm device 47 still remains connected to panel terminal 8 through theunbroken portion of the house loop conductor 46. Panel terminal 8 is inturn connected to panel terminal 3 through the closed run-down contacts2-12. When the contacts of the alarm device 47 close, the winding 3-01of the alarm relay 3-00 will be shunted and the alarm relay 3-00 willthereupon release. Release of the alarm relay 3-00 causes transmissionof a tire signal by the fire clock 1-00 in the same manner as thatdescribed above for normal circuit conditions of the house loopconductors.

Grounded circuit trouble condition As previously described, one end ofthe winding 4-01 of trouble relay 4-00 is connected substantiallydirectly to the negative panel terminal 7. The other end of the winding4-02 is connected to the positive panel terminal 8 over a supervisorycircuit which includes both of the house loop conductors 45 and 46connected in series. Negative panel terminal 7 is normally groundedthrough rundown contacts 2-13 of the trouble clock 2-00. As a result, aground on either of the loop conductors 45 or 46 will shunt the winding4-01 of trouble relay 4-00 by causing both ends of the winding to begrounded, one

end being grounded through run-down contacts 2-13 and the other throughthe circuit fault.

If the ground is on house loop conductor 45, both the alarm relaywinding 3-01 and the trouble relay winding 4-01 will be shunted out.Excessive current flow will be prevented by the current limitingresistor 28. Both the alarm relay 3-00 and the trouble relay 4-00 willbe released simultaneously and the trouble signal will be transmitted asdescribed above. After transmission of the trouble signal has beencompleted trouble circuit conditions will be established as describedabove and as shown in Fig. 3.

In the trouble circuit condition of Fig. 3, the ground circuitconnection from panel terminals 9 and 10 to negative panel terminal 7 isbroken at the run-down contacts 2-13. The supply is ungrounded. So longas there is a ground fault only on a single one of the house loopconductors 45 and 46, the fault will have no eliect because it is theonly ground connection to the system, the normal ground connectionhaving been broken by run-down contacts 2-13 of the trouble clock.Operation of the system with the ground fault will therefore be the sameas that described above for the open circuit trouble condition. Thiswill be apparent from Fig. 3, assuming a ground fault to be present at54. Because the normal ground connection has been broken by the troubleclock run-down contacts 2-13, the only ground on the system consists ofthe ground fault indicated at 54 which will have no effect on theoperation of the system since the system is otherwise ungrounded.

Change of retard interval As previously described, it has been assumedthat there will be a 30 second delay between the opening of contacts3-02 of the alarm relay 3-00 and the tripping of the release magnet 1-03of the fire clock 1-00 to initiate the four rounds of fire signal. Sucha delay interval is appropriate for a water flow alarm in an automaticsprinkler system.

In an aero system, in which a sudden rise in temperature caused by afire produces an abrupt increase in air pressure in pneumatic tubingextending throughout the protected area, a 30 second delay is notrequired. The 30 second delay, which is necessary to avoid water hammerefiects may be considerably shortened in an aero system. For thispurpose, a resistor 50 is provided which may be connected in multiplewith the capacitor 36 so that its discharge time is shortenedaccordingly. A delay interval of 12 seconds is suitable in the case ofan aero system.

As shown in Pig. 2, one terminal of the resistor 50 is connected to aterminal screw 41 on the panel 10. The positive terminal of theelectrolytic capacitor 36 is connected to a terminal screw 42 on thepanel 18. The other terminal of the resistor 50 and the negativeterminal of the capacitor 3e are both connected to the negative supplyconductor 25. When terminal screws 41 and 42 are connected together, theresistor is connected directly multiple with the capacitor so that itsdischarge time with reference to the fire clock release magnet 1-03 isreduced from 30 seconds to 12 seconds.

When the 30 second delay is used, a nameplate 40 of insulating material(Fig. 4) is mounted on the termirial screws 41 and 42. As shown in Fig.1, the insulating nameplate '40 bears the legend Waterflow FlowTransmitter-Long Retard. This indicates to a user of the transmitterthat it is arranged for operation with an automatic sprinkler system. Inthis case the resistor 50 is disconnected. In the case of an aerosystem, a metal nameplate 43 is mounted on the terminal screws 41 and42, as shown in Fig. 5. The metal nameplate 43 bears a suitable legend(not shown) indicating that the transmitter is arranged to provide ashort retard interval. Being made of metal, the nameplate 43 establishesan electrical connection between the terminal screws 41 and 42 and thusconnects the resistor 50 in multiple with the capacitor 36 to reduce itsdischarge time.

Operation of the tamper switch As previously described, the tamperswitch has 'a closed circuit position in which it is held by the door ofthe cabinet in which the transmitter is enclosed while the cabinet doorremains closed. If the cabinet door is opened, the supervisory circuitis broken by the tamper switch 20 and the trouble clock transmits atrouble signal in the usual manner. If the cabinet door has been openedby some unauthorized person, the operator at the central ofiice willdispatch repair personnel to the protected premises. If however, thedoor is opened for purposes of inspection and maintenance, the inspectorwill operate the tamper switch manually to another closed position inwhich it will remain closed while the cabinet door is open. Thisrecloses the supervisory circuit for purposes of routine testing andinspection.

, After the testing and inspection have been completed, the troubleclock is fully wound by the application of a key to its winding stem2-01 so that the run-down contacts 2-11 to 2-14 are brought to theirrespective normal conditions. In thecase of an intermittent ground orbreak, the cam 206 is advanced step by step until contacts 208 ride upon the face of cam 206 and remain open throughout the duration of thetrouble signal, closing at the end of this signal so that the mechanismcan be rewound.

When the trouble'clock is operated to transmit a trouble signal, thecontacts 2-09 open again making the release magnet 2-03 independent ofthe condition of the trouble relay 4-00. In this manner, an intermittenttrouble condition which will operate and release the trouble relay 4-00cannot interfere with the transmission of the trouble signal byintermittently energizing the trouble clock release magnet winding 2-04during transmission of the trouble signal. The cam actuated contacts2-09 thus insure that a trouble condition of short duration cannot stopthe trouble clock with its contacts 2-08 actuated by a code wheel toothso that the central olfice circuit is left open or grounded.

In the case of the shunt contacts 27 at the right in Fig, 2, it isdesirous to remove the shunt as soon as the four rounds are completedand the clock is stopped, so that any other transmitter protectinganother part of the building will not be inoperative while the firsttransmitter remains in the fire signal condition.

While the clock mechanisms have been referred to as fire and troubleclocks, it will be appreciated that this is for identification ratherthan forlimiting purposes, and this is true of other terms employedherein. The fire clock may be considered an alarm transmitting unit andthe trouble clock a unit for detecting faults such as breaks or groundsin the transmitting circuits and for curing or eliminating those faultsto keep the fire clock in alarm transmitting condition .The transmitteras a whole has been designed to work in with any of the accepted andmore or less standard fire protection'systems and for that reason isoperative on the McCullogh circuit and utilizes, where possible,conventional proven parts such as a Spies recycling cam on the fireclock and the like.

Being completely automatic and self-supervising, this transmitter isparticularly suited to the protection of present-day establishmentswhich, as a general rule, are closed and left unattended over theweek-end periods from Friday to Monday.

The resistor 31 in series with the capacitor 36 prevents the sending inof a false alarm if the capacitor for any reason should short circuit,and this also prevents injury or destruction of contacts 3-02 in theevent of a capacitor short circuit.

The insulating cam 2-06 on the trouble mechanism makes it possible toclose the door with any type tamper switch such as now in use andprevents an intermittent trouble, such as a break or ground, fromleaving the central office circuit open or grounded if the clock shouldstop with the central oifice springs on a tooth of the signal wheel2-05.

The power failure current relay 5-00 by transferring the central officewires 24 to a distinct current failure signal wheel 1-06 on the fireclock 1-00, makes it unnecessary to put a retard on the trouble clock.The insulating cam 1-11 on the fire clock enables the engineer in chargeto shut off local signal bells any time after completion of a four-roundfire signal and the shunt contacts 1-13 open at the end of four roundsof fire signal, so that any other transmitter in the same building cansend in signals to the central office.

The fundamental circuit, as indicated in Fig. 3, will detect a ground oneither leg of the house loop, as distinct from prior transmitters whichonly detect grounds on first one leg, condition the circuit and thendetect 0 the other leg.

What is claimed is:

1. An alarm system comprising a spring driven fire clock having arelease magnet, said fire clock being operative to transmit a firesignal upon deenergization of its release magnet; a spring driventrouble clock having a release magnet, said trouble clock beingoperative to transmit a trouble signal upon deenergization of itsrelease magnet; a source of current; an alarm relay having an operatingwinding and contacts connecting said fire clock release magnet forenergization from said source when said alarm relay winding isenergized; a trouble relay having an operating winding and contactsconnecting said trouble clock release magnet for energization from saidsource when said trouble relay winding is energized; a closedsupervisory circuit energized from said source and including both ofsaid relay operating windings connected in series; further contacts onsaid trouble relay connected to energize said fire clock release magnetindependently of said alarm relay contacts when said trouble relaywinding is deenergized; and an alarm signal device connected to saidsupervisory circuit, said alarm device having contacts connected toshunt out said alarm relay winding while maintaining current flow insaid supervisory circuit for causing transmission of said fire signal,whereby closure of said alarm device contacts will operate said fireclock independently of said trouble clock and an open circuit conditionin said supervisory circuit will operate said trouble clockindependently of said fire clock.

2. An alarm system according to claim 1, further comprising a panel onwhich said clocks and said relays are mounted, said supervisory circuitextending exteriorly of said panel as a two-wire circuit to said alarmdevice contacts and back to said alarm relay winding, said trouble clockfurther comprising run-down contacts actuated after operation of saidtrouble clock to transmit a trouble signal, said run-down contactsseparately connecting each end of said alarm relay winding to both endsof one of the wires of said two-wire circuit, whereby said alarm relaywinding may be shunted by said alarm device contacts notwithstanding abreak in said two-wire circuit.

3. An alarm system according to claim 2, in which said source isungrounded, said system further comprising ad- :ditional run-downcontacts actuated along with said first named run-down contacts, and aground connection extending through said additional run-down contacts tothe side of said source which is electrically nearer said trouble relaywinding than to said alarm relay winding, whereby .said trouble relaywinding will be shunted in the event of a ground fault on said two-wirecircuit, said additional contacts opening after transmission of saidtrouble signal so that the only ground on said supervisory circuit issaid ground fault.

4. An alarm system according to claim 1, further comprising a currentfailure relay having a winding connected to said source, one of saidclocks having circuit means oeprative during the running of said oneclock for transmitting a distinctive current failure signal, saidcurrent failure relay comprising contacts actuated upon deenergrzationof its Winding to render said circut means operative to transmit saiddistinctive signal and to render -both of said clocks simultaneouslyinoperative to transmit either of their normal sginals.

5. An alarm system according to claim 1, further comprising a capacitorconnected to said fire clock release magnet for prolonging itsenergization when it would otherwise be deenergized, whereby said alarmdevice contacts must be closed for a predetermined minimum time=contacts, deenergization of said trouble clock winding causing thetransmission of a trouble signal over said central ofiice circuit; asource of current; an alarm relay having an operating winding andcontacts which connect said fire clock winding for energization fromsaid source when said alarm relay is operated; a trouble relay having anoperating winding and contacts which connect said trouble clock Windingfor energization from said .source when said trouble relay is operated;a closed supervisory circuit continuously energized from said source,both of said relay operating windings being serially. included in saidsupervisory circuit in series with each other for maintaining saidrelays operated; an alarm device having contacts connected to saidsupervisory circuit for separately shuntin said alarm relay winding torelease said alarm relay independently of said trouble relay winding;and further contacts on said trouble relay connected to energize saidfire clock windin independently of said alairn relay contacts when saidtrouble relay is released, whereby closure of said alarm device contactswill cause transmission of a fire signal independently of said troublesignal and a break in said supervisory circuit will cause transmissionof said trouble signal independently of. said lire signal.

7, An alarm system according to claim 6, further comprising a panel uponwhich said clocks and said relays are mounted, said supervisory circuitextending as a twowire circuit from said panel to said alarm devicecontacts and back to said alarm relay operating winding; and run-downcontacts included in said trouble clock, said run-down contacts beingoperative after transmission of said trouble signal separately toconnect the opposite ends of each wire of said two-wire circuittogether, whereby said supervisory circuit is closed notwithstanding abreak in said two-wire circuit and said alarm device contacts areconnected to shunt said alarm relay winding notwithstanding said circuitbreak.

8. A11 alarm system according toclaim 6, wherein said source isungrounded, one terminal of said source being connected substantiallydirectly to one side of said trouble relay winding, the other terminalof said source being connected to said source through said supervisorycircuit, said system further comprising normally closed run-downcontacts in said trouble clock, said run-down contacts opening aftertransmission of said trouble signal, and a ground connection extendingto said other terminal of-said source through said run-down contacts,whereby a ground fault on said supervisory circuit will shunt saidtrouble relay winding thereby causing said trouble clock to transmit atrouble signal, whereafter said rundown contacts will open leaving saidground fault as the only remaining ground connection to said supervisorycircuit.

9. An alarm system according to claim 6, in which said source suppliesdirect current, said system further comprising a capacitor connected inparallel with said fire clock release magnet winding for prolonging theenergization thereof, whereby said alarm device contacts must remainclosed for a predetermined minimum time interval before said fire clockwill transmit said first signal.

10. An alarm system according to claim 9, wherein said capacitor is anelectrolytic capacitor, said system further comprising a rectifierconnected in series with the parallel combination of said fire clockwinding and said capacitor, said rectifier being so poled that said fireclock winding can be energized only when the polarity of said source iscorrect with respect to the polarity of said electrolytic capacitor.

11. An alarm system according to claim 9, further comprising additionalcode wheel actuated contacts in said fire clock for transmitting adistinctive current failure signal; a current failure relay having awinding connected to said source, said current relay having contactseffective upon deenergization of its Winding to disconect saidfirstnamed code wheel actuated contacts from said central ofiice circuitand to substitute said additional code wheel actuated contacts therefor,said current relay having further contacts connected in series with saidfire clock winding for completely deenergizingsaid fire clock windingindependently of said capacitor and said alarm and trouble relaycontacts immediately upon deencrgization of said current relay winding.

12. In an alarm transmitter having a fire clock and a trouble clock; arelease magnet for each clock, deenergization of either of said releasemagnets initiating operation by its associated clock; code wheelactuated contacts included in each clock for the transmission ofrespective fire and trouble signals thereby; further code wheel actuatedcontacts included in one of said clocks for transmitting a distinctivecurrent failure signal during operation thereof; an energizing circuitadapted for connection to a current source for normally continuouslyenergizing both of said release, magnets; a current failure relay havingan operating winding connected to said energizing circuit; and contactsincluded in said relay and responsive to failure of said current sourcefor rendering said firstnamed code wheel actuated contacts inoperativeand said further code wheel actuated contacts operative.

References Cited in the file of this patent UNITED STATES PATENTS2,032,092 Johnson et al. Feb. 25, 1936 2,122,222 Vingerhoets June 28,1938 2,530,749 Yardeny Nov. 21, 1950 2,594,069 Poehlmann Apr. 22, 19522,699,541 Ward Jan. 11, 1955

